The present invention relates to the field of formation degradation and more specifically pavement milling. A milling machine may comprise a driving mechanism populated with a plurality of degradation assemblies, typically picks or cutters, which may degrade natural or man-made formations such as pavement, concrete, or asphalt when the driving mechanism is rotated while in contact with the formation. During normal milling operation, the degradation assemblies are often damaged due to coming into contact with hard materials buried underneath or located on the surface of the formation. The prior art discloses milling assemblies for improving the service life of said degradation assemblies.
One such milling assembly is disclosed in U.S. Pat. Pub. No. 2008/0284235 to Hall et al., which is herein incorporated by reference for all that it contains. Hall et al. discloses an apparatus for degrading natural and man-made formations including a pick with an axially spring loaded pick comprising a central axis and being attached to a holder secured to a driving mechanism. The pick comprising a steel body with an axial shank disposed within a bore of the holder. A spring mechanism may be built into the holder which allows the tip to engage the formation and then recoil away from the formation lessening drag that would otherwise occur on the tip. The recoiling effect is believed to reduce wear caused from the drag. The recoiling effect is also believed to degrade the formation in larger chunks than dragging the tip against the formation surface. The spring mechanism may comprise a coil spring, a compression spring, a tension spring, Belleville spring, wave spring, elastomeric material, gas spring, or combinations thereof. The pick may also comprise an axial shank which is press fit into the holder. The shank is secured within a holder which is secured to the driving mechanism.
Another such milling assembly is disclosed in U.S. Pat. No. 4,175,886 to Moench et al., which is herein incorporated by reference for all that it contains. Moench et al. discloses an asphalt cutting apparatus for breaking up and windowing old asphaltic pavement on a roadway or the like including the pavement adjacent to a curb or gutter. A plurality of laterally spaced, sharpened cutter discs are freely rotatably mounted on a support carriage. The support carriage is attached to a frame pivotally coupled at a forward pivot to a prime mover such as a truck or similar vehicle for movement along the asphalt surface. As the cutter discs are moved along the asphalt surface a hydraulic clamp cylinder provides a vertical movement about the forward pivot to vary the depth of cut and also maintains a downward pressure on the cutter discs and forces the discs to roll through and cut up the asphalt.
The construction and mounting of the support carriage is such that the discs are adjustably movable laterally axially along a horizontal axis for selective positioning adjacent to a curb or gutter and are further adjustably movable about a pivot to slope laterally outwardly and downwardly so that the discs are positioned at different cutting depths relative to one another for cutting an asphalt surface that is sloped for drainage purposes.